Thought

Political philosophy

Nozick's Anarchy, State,
and Utopia (1974), which received a National Book Award, argues among other
things that a distribution of goods is just if brought about by
free exchange among consenting adults and from a just starting
position, even if large inequalities subsequently emerge from the
process. Nozick appealed to the Kantian idea that people should be treated as
ends (what he termed 'separateness of persons'), not merely as a
means to some other end. Nozick here challenges the partial
conclusion of John Rawls's Second Principle of Justice of his
A Theory of Justice,
that "social and economic inequalities are to be arranged so
that they are to be of greatest benefit to the least-advantaged
members of society."

Anarchy, State and Utopia claims a heritage from John
Locke's Second Treatise on Government and tries to base
itself upon a natural law doctrine. Locke only relied on natural
law as God given to counteract the King of England's claim to
divine right and thus claim to all the
property of England. Nozick suggested, again as a critique of
utilitarianism, that the sacrosanctity of life made property rights
non-negotiable. This principle has served as a foundation for many
libertarian pitches into modern politics.

Most controversially, Nozick argued that a consistent upholding of
the libertarian non-aggression
principle would allow and regard as valid
consensual/non-coercive enslavement contracts between adults. He
rejected the notion of inalienable rights advanced by most other
libertarian academics, writing in Anarchy, State and
Utopia:

"The comparable question about an individual is whether
a free system will allow him to sell himself into
slavery.

Nozick's third and fourth conditions are counterfactuals. Nozick calls his theory the
"tracking theory" of knowledge. Nozick believes that the
counterfactual conditionals bring out an important aspect of our
intuitive grasp of knowledge: For any given fact, the believer's
method must reliably track the truth despite varying relevant
conditions. In this way, Nozick's theory is similar to reliabilism.

Utilitarianism

Nozick created the thought experiment of the "utility monster" to show that average
utilitarianism could lead to a situation where the needs of the
vast majority were sacrificed for one individual. He also devised
the thought experiment of The
Experience Machine in an attempt to show that ethical hedonism
was false. Nozick asked us to imagine that "superduper
neuropsychologists" have figured out a way to stimulate a person's
brain to induce pleasurable experiences. We would not be able to
tell that these experiences were not real. He asks us, if we were
given the choice, would we choose a machine-induced experience of a
wonderful life over real life? Nozick says no, then asks whether we
have reasons not to plug into the machine and concludes that since
it does not seem to be irrational to plug in, ethical hedonism must
be false.

Unusual method

Nozick was notable for his curious exploratory style and
methodological ecumenism. Often content to
raise tantalizing philosophical possibilities and then leave
judgment to the reader, Nozick was also notable for drawing from
literature outside of philosophy (e.g., economics, physics,
evolutionary biology).